DC-DC converters are needed in almost every commercial product, whether it is industrial, medical, defensive, automotive, or any other application. These converters are electronic circuits that can convert the DC voltage from one level to another.
There are two types of DC-DC converters: linear and switching converters. Linear converters are resistive which means that they use resistive voltage drop to create a regulated output voltage. This also means that the input voltage should always be higher than the input voltage, and linear converters can only step down a voltage level. On the other hand, switching converters perform the conversion by storing the energy periodically in the energy storage elements like capacitors and inductors. The stored energy is then provided to the load at the desired voltage level.
There are several benefits of switching converters. Firstly, switching converters are highly efficient. They have an efficiency in the range of 80-90%. Moreover, the buck-boost converters can step up and down the voltage levels to maintain the output voltage. Additionally, thermal management is simplified due to lower losses.
SEPIC (Single Ended Primary Inductor Converter) type of converter is very similar to the traditional buck-boost converters. SEPIC can step up as well as step down the voltages accordingly. The simple buck-boost converters consist of two MOSFETs used as switches. SEPIC converters, however, are characterized using two inductors, one of them is at the input that is for coupling, and another one is connected to the ground.The SEPIC topology consists of an input capacitor, an output capacitor, coupled inductors, a diode, and a power MOSFET. To understand the working of the SEPIC, let’s assume that the switch is first open. In this state, it can be easily seen that the input capacitor Cin is charged at the input voltage.